1. 可变容器通用方法（Common operators (methods) on mutable collections）
c += x：把x元素添加到集合c中
scala> val a = collection.mutable.ArrayBuffer(1,2,3)a: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(1, 2, 3)scala> a += 4res15: a.type = ArrayBuffer(1, 2, 3, 4)
c += (x,y,z)：把x，y，z添加到集合c中
scala> val a = collection.mutable.ArrayBuffer(1,2,3)a: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(1, 2, 3)scala> a += (4,5,6)res16: a.type = ArrayBuffer(1, 2, 3, 4, 5, 6)
c1 ++= c2：把集合c2的元素全部添加到集合c1中
scala> val c1 = mutable.ArrayBuffer(1,2,3)c1: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(1, 2, 3)scala> val c2 = mutable.ArrayBuffer(4,5,6)c2: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(4, 5, 6)scala> c1 ++= c2res20: c1.type = ArrayBuffer(1, 2, 3, 4, 5, 6)
c -= x：在集合c中删除元素x
scala> val c = mutable.ArrayBuffer(1,2,3)c: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(1, 2, 3)scala> c -= 3res21: c.type = ArrayBuffer(1, 2)scala> c -= 7res22: c.type = ArrayBuffer(1, 2)
c -= (x,y,z)：在集合c中删除元素x，y，z
scala> val c = mutable.ArrayBuffer(1,2,3,4,5)c: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(1, 2, 3, 4, 5)scala> c -= (3,4)res23: c.type = ArrayBuffer(1, 2, 5)
c1 --= c2：删除集合c1中所有在c2中存在的元素
scala> val c1 = mutable.ArrayBuffer(1,2,3,4,5)c1: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(1, 2, 3, 4, 5)scala> val c2 = mutable.ArrayBuffer(2,4)c2: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(2, 4)scala> c1 --= c2res24: c1.type = ArrayBuffer(1, 3, 5)
c(n) = x：把集合c中第n个元素赋值为x
scala> val c = mutable.ArrayBuffer(1,2,3,4,5)c: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(1, 2, 3, 4, 5)scala> c(2) = 8scala> cres26: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(1, 2, 8, 4, 5)
c clear：删除集合c中的所有元素
scala> val c = mutable.ArrayBuffer(1,2,3,4,5)c: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(1, 2, 3, 4, 5)scala> c.clearscala> cres28: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer()
c remove(n)：在集合c中删除第n个位置的元素，并返回该元素
scala> val c = mutable.ArrayBuffer(1,2,3,4,5)c: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(1, 2, 3, 4, 5)scala> c.remove(3)res29: Int = 4scala> cres30: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(1, 2, 3, 5)
c remove(n,len)：在集合c的第n个元素开始，删除len个元素
scala> val c = mutable.ArrayBuffer(1,2,3,4,5)c: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(1, 2, 3, 4, 5)scala> c.remove(1,2)scala> cres32: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(1, 4, 5)
2. 可变容器通用方法（Immutable collection operators）
下面我们来展示不可变容器的通用操作方法。不可变容器内容是不可变的，所以制定一个新的变量来接受这些方法的返回值。
c1 ++ c2：返回集合c1和集合c2的并集
scala> val v1 = Vector(1,2,3)v1: scala.collection.immutable.Vector[Int] = Vector(1, 2, 3)scala> val v2 = Vector(4,5,6)v2: scala.collection.immutable.Vector[Int] = Vector(4, 5, 6)scala> val v = v1 ++ v2v: scala.collection.immutable.Vector[Int] = Vector(1, 2, 3, 4, 5, 6)
c :+ e：返回一个新的集合，内容为集合c添加元素e形成的新集合
scala> Vector(1,2,3) :+ 4res34: scala.collection.immutable.Vector[Int] = Vector(1, 2, 3, 4)
e +: c：返回一个新的集合，内容为元素e追加到集合c前面形成的新集合
scala> 4 +: Vector(3,2,1)res35: scala.collection.immutable.Vector[Int] = Vector(4, 3, 2, 1)
e :: List：返回新的List，内容为元素e追加到List集合前形成的新List
scala> 4 :: List(3,2,1)res37: List[Int] = List(4, 3, 2, 1)